Natural and synthetic zeolitic crystalline metalosilicates are useful as catalysts and adsorbents. Metalosilicate molecular sieves are zeolites with a silicate lattice wherein a metal can be substituted into the tetrahedral positions of the silicate framework. These metals include aluminum, gallium iron and mixtures thereof. These metalosilicates have distinct crystal structures which are demonstrated by X-ray diffraction. The crystal structure defines cavities and pores which are characteristic of the different species. The adsorptive and catalytic properties of each crystalline metalosilicate are determined in part by the dimensions of its pores and cavities. Thus, the utility of a particular zeolite in a particular application depends at least partly on its crystal structure.
Because of their unique molecular sieving characteristics, as well as their catalytic properties, some crystalline metalosilicates are especially useful in such applications as gas drying and separation and hydrocarbon conversion. Although many different crystalline aluminosilicates, borosilicate and silicates have been disclosed, there is a continuing need for new zeolites and silicates with desirable properties for gas separation and drying, hydrocarbon and chemical conversions, and other applications.
Crystalline aluminosilicates are usually prepared from aqueous reaction mixtures containing alkali or alkaline earth metal oxides, silica, and alumina. "Nitrogenous zeolites" have been prepared from reaction mixtures containing an organic templating agent, usually a nitrogen-containing organic cation. By varying the synthesis conditions and the composition of the reaction mixture, different zeolites can be formed using the same templating agent Use of N,N,N-trimethyl cyclopentylammonium iodide in the preparation of Zeolite SSZ-15 molecular sieve is disclosed in U.S. Pat. No. 4,610,854; use of 1-azoniaspiro [4.4] nonyl bromide and N,N,N-trimethyl neopentylammonium iodide in the preparation of a molecular sieve termed "Losod" is disclosed in Helv. Chim. Acta (1974); Vol. 57, p. 1533 (W. Sieber and W. M. Meier); use of quinuclidinium compounds to prepare a zeolite termed "NU-3" is disclosed in European Patent Publication No. 40016; use of 1,4-di(1-azoniabicyclo[2.2.2.]octane) lower alkyl compounds in the preparation of Zeolite SSZ-16 molecular sieve is disclosed in U.S. Pat. No. 4,508,837; use of N,N,N-trialkyl-1-adamantamine in the preparation of Zeolite SSZ-13 molecular sieve is disclosed in U.S. Pat. No. 4,544,538, and for SSZ-24 in U.S. Pat. No. 4,665,110.
Synthetic zeolitic crystalline borosilicates are useful as catalysts. Methods for preparing high silica content zeolites that contain framework boron are known and disclosed in U.S. Pat. No. 4,269,813. The amount of boron contained in the zeolite may be made to vary by incorporating different amounts of borate ion in the zeolite-forming solution. In some instances, it is necessary to provide boron as a pre-formed borosilicate.
The present invention relates to a novel family of stable synthetic crystalline materials identified as SSZ-31 and having a specified X-ray diffraction pattern, and also to the preparation and use of such materials.